X-ray diffraction apparatus



March 6, 1951' K. E. BEU :1- AL X-RAY DIFFRACTION APPARATUS VENT INLET INVENTORS KARL E BEU HOWARD H.CLAASSEN ATTORNEY; 2

2 4 5 4 I. 6 4 8 5 5 4 V. B 3 O s Q 8 6 9 0 7 4 w & o 5 8 4 n v l 2 m 8 3 l l 8 3 l 3 w 9 m 7 2 Q m 9 99 7 4 8w 5 9 I G 7 4 8 F 6 E 4 2 O M n 5 9 l m 0 a 2 l 8 9 6 a 2 Q a, 8 7 l 6 l 6 O I 23% l w E 5 8 x 4 6 6 2 l 6 6 6 2 9 m L 2 Patented Mar. 6, 1951 Karl E. Beu, Bartlesville, and Howard H. Claas- 7 son, Norman,'0kla., assignors to Phillips Petroleum Company, a corporation of Delaware Application April 26, 1948, Serial No. 23,234

9 Claims.

This invention relates to X-ray diifraction apparatus. In one more specific embodiment, it relates to such apparatus embodying cooling means for transforming a normally liquid or I gaseous substance into a frozen crystalline state for X-ray analysis thereof. Heretofore, X-ray-machines have been commonly used to obtain diffraction patterns of crystalline materials and thereby determine the crystal structure thereof. When such apparatus is used with substances which are liquid or gaseous at room temperatureand hence have no crystalline structure, it is necessary to cool the specimen below its freezing point in order to obtain the material in crystalline form suitable for examimeans areprovided for hermetically sealing the X-ray chamber and for preventing light from en tering the chamber after the film has been exposed. Provision is also desirably made for rotation of the specimen holder assembly while the film is being exposed to reinforce the difiraction pattern obtained from the impingement of the X-ray beam upon the specimen.

nation by the X-ray diffraction apparatus. Many attempts and proposals have been made to devise satisfactory apparatus for use under such conditions but none of these has been completely successful on a practical and commercial scale due to the difiiculties enountered in maintaining a constant low temperature in thespecimen-holder and in freezing the specimen rapidly to obtain small crystals. Other difiiculties are encountered as a result of leaks at the vacuum seals in the X-ray chamber and fogging of the film provide the necessary crystal structure for X-ray examination." This result may be advantageously accomplished by providing an inner chamber or subchamber-within the main X-ray chamber into which a cooling fluid, such as liquidnitrogen, is introduced to rapidly decrease the temperature of the specimen. This chamber is preferably formed by engagement of two relatively movable members which surround the specimen holder and define a sealed region adjacent thereto. In order to prevent interference with the X-ray beam by the subchamber walls, we provide for the disengagement of said members after the specimen has been cooled to the desired degree but before the X-ray photograph is taken. It is a feature of the invention that a thermocouple and heater are provided adjacent the specimen holder-to obtain close control of specimen tempera ture while the actual photograph is taken. Further in accordance with the invention, novel Accordingly, it is an object of the invention to provide improved apparatus for obtaining an X- ray diffraction photograph of a specimen which is maintained at low temperature.

It is a further object of the invention to provide an X -ray diffraction camera in which a sub,- chamber or inner chamber is provided within the main X-ray apparatus into which cooling fluid may be introduced for quickly freezing a specimen under test.

It'is a still further object of the invention to provide such an X-ray diffraction apparatus which is of simple construction, rugged, durable, and economical to build and adjust.

Various other objects, advantages and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a sectional view of the novel X-ray diffraction apparatus;

Figure 2 is a detail view of the X-ray slit assembly; and r V Fi ure 3 is a detail view of the specimen holder.

Referring now to the drawings in detail, the apparatus comprises a generally cylindrical main X-ray chamber In defined by a base II and a housing I2 which is secured to the base by alignment screws, as at l3, a vacuum sealbetween these parts being provided by a gasket 14. The chamber l0 may be hermetically sealed in the manner hereinafter described and it may be ex-. hausted by a suitable suction line secured to a port i5 communicating with the interior of the chamber.

Mounted in the chamber [0 is a guide or slit assembly l8 which directs a beam of X-rays against a specimen contained within a holder 19, this specimen reflecting a part of the X-ray beam in such fashion as to form a diffraction pattern upon a film 20 which is held against the inner arcuate portion of the housing [2. The part of the beam which is not reflected by the specimen is absorbed bya beam stop 2| to prevent fogging,

of the film, the stop being supported interiorly of the chamber ID by a screw 22. As will become apparent. fromthe following description, when the X-ray apparatus isenergized, the parts are in such position as to provide a clear unobstructed path between the inner end of the slit assembly, the specimen, the beam stop, and the film.

The slit assembly, as shown in detail by Figure 2, comprises a pair of fiat members 24, 25 which are held together by a sleeve 25 and define a longitudinally-extending slit 21. As shown, the members 24, 25 are tapered, thereby providing a rela tively thin forward edge which permits diffraction patterns to register on the film at large angles. e

Referring again to Figure 1, an outer liner 28 is superposed upon the sleeve 25 and this liner fits into a complementary recessed portion 29 formed in the housing l2. The assembly is secured within the recessed portion 29 by an apertured cap 30 which is screw threaded on the housing I2 and an apertured gasket 3 l is provided for sealing the outer end of the slit assembly. A beryllium disc or window 32 is disposed between the cap 30 and the gasket, this window being transparent to X-rays but effectively preventing the entranceof air and light into the chamber ID and resultant fogging of the film. The disc 32 also seals the apertured portions of the cap and gasket. It will be apparent that, when a source of 2 -ra ys is placed adjacent the aperture in cap 30, a beam will be directed against the specimen in holder l9 thereby impressing a diffraction pattern upon the film 20.

In order that the film may be readily inserted and removed, we provide a film support comprisin a metalring 35 which rests upon the base I l and an annular member 36 which is supported at the top of the chamber by the screw 22. The ring 35 has a flanged portion 3'! which, together with the adjacent surface of the housing, defines a narrow slot for receiving the lower end of the film while the member 36 is of uch dimensions as to define a narrow slot with the adjacent surface of the housing for receiving the upper end of the film. Thisstructure provides a support which positively holds the film in position, let the film may be readily inserted into the holder or removed therefrom. A After the film is exposed, it is oftentimes desirable to disconnect the X-ray generator and suction line sothat the apparatus may be moved into a darkroom for removal of the film. V In such cases, it is necessary to prevent light from entering through port [5 and fogging the film. To this end; we provide an exhaust tube 40 communicating with the port l5 and chamber II], this tube being provided with a threaded nut 4| carrying a rod which, in turn, carries a cap 43, this cap being engageable with the inner end of the tube 40. Two sets of threads 44, 45 are provided on the nut 4| and, when threads 44 engage mating threads formed interiorly of the tube 4!], a seal is effected at the threaded joint and the cap 43 protrudes inwardly of the chamber, as shown. The interior of the chamber may then be exhausted through port l5 in the usual manner. When it is desired to restore normal air pressure within the chamber, the nut 4! is moved outwardly to disengage threads 44 and permit air to enter the chamber through tube 40. Thereafter, the nut 4| isagain moved outwardly until threads 45 are engaged, thereby causin the cap 43 to fit against the inner end of the tube 40. This prevents light from entering the chamber through the port I when the suction line is disconnected therefrom and the apparatus may then be moved into a darkroom without fogging the film.

We also provide windows, one of which is shown at 46, for observing the interior of the chamber l0. These windows may be covered with suitable plugs to exclude light when the apparatus is in use.

The specimen holder l9 preferably comprises a beryllium tube, the interior of which is of capillary dimensions so that as'mall quantity of liquid may be retained therein by capillary action. The tube may thus be used many times by pushing or blowing one specimen through the tube and replacing it by another. Beryllium is the preferred material for the tube due to its transparency to X-rays and the fact that it is insoluble in hydrocarbon specimens. In addition, the beryllium tube conducts heat away from the specimen rapidly, enabling a low specimen temperature to be maintained. Such a tube may be advantageously formed by depositing beryllium vapors in a vacuum upon a rotating copper rod of small dimensions, Thereafter, the copper rod may be dissolved bya suitable etchin reagent, such as nitric acid, which will attack the copper but not the beryllium. The preferred dimensions for the tube ar' e a diameter of about 0.5mm. and a wall thickness of about 0.01 mm. The specimen holder or tube [9 is held by an assembly which is screw thr'eaded into a tubular member 49. As shown in detail by Figure 3, the assembly 48 comprises a nut 50 having a central passage into which the tube I9 is soldered. The nut 50, in turn, is screw threaded to a generally cylindrical member 5|, having a frustrmconical portion 52 together with a shoulder 53 and, threads 54 by which it is secured to the end of the tube 45. k

A thermocouple, 55 is positioned at the lower end of the member 5|, one terminal of the thermocouple being connected to said member and the other terminal having a lead, not shown, connected thereto which extends through a bore 56. A heater coil 51 is wound around the lower end of the member 5!, this coil having one termian connected to a lead, not shown, which extends through a glass bead insulator 58, this in sulator also forming a vacuumseal for the speciinen hold'r assembly. Thefother heater termi- 'nal has a lead, not shown, extending through a bore59 in the member 5|. Thus, the thermocouple indicates the temperaturein the region of the specimen and the heat-er coil may be used to raise the tem erature if itbecomes too low.

The tube 49 which carries the specimen holder unit 48 forms a part oi? a rotatable assembly 62 and the tube is mov'able 'axially with respect to this assembly by virtue of a threaded connection 63 between the tube and a perforated annular nut member 64 secured to a cylindrical housing 65. Thus, rotation'of the tube by 'a knob 66 secured thereto causes it to move l'o'ngitudinally of the housing 65 and assembly. 62. The knob has an internal passage communicating with the passage in tube 4'}! and a Jones type connector plug "6'! is seated in th sassage. The leads previously described for maki'n'g connection to the heater 'a n'dthermocouple in specimen holder assembly '48 extend through the tube 49 and terminate at plug 67 thereby 'aifording convenient electrical connections for these parts.

,The assembly 62 carrying the specimen holder T9 is rotatable as a am, such rotation of the spec'zimen whilev the, X-ray device is energized being'efiective to improve the uniformity of the diiiraction pattern registered on the film, as those '75 skilled in theart understand. A metal ring "I9 is screw threaded to the bottom of the housing 65 and a sleeve 1| is screw threaded to the ring I9, this sleeve carrying a bearing race I2 which cooperateswith roller bearings I3 and a bearing race I4 on the housing I2. Rotation of the assembly 62 and specimen holder I9 upon the bearings I3 is effected by a motor I6 which drives a gear I! meshing with a ring gear I8 secured to an ring I9. A pair of gaskets 83, 84 provide a vacuum seal for the, shim 8| at the respective inner and outer surfaces thereof. It will be apparent that, when the motor I6 is operated, ring gear I8 and plate 19 are rotated thereby rotating the assembly 62 and the specimen holder I9 through shim 8|. It will be noted that the shim 8| provides vertical compliance between the assembly 62 and the lower part of theapparatus, thereby overcoming alignment problems in assembly.

As an optional feature, we provide means for reversing the direction of motor rotation each 360 of motor revolution. To this end, a tooth 85 is provided upon the periphery of the annular member I9 and this tooth actuates a switch 86- each time the annular member I9 makes a complete revolution. The switch is connected to the motor in a suitable circuit so that the direction of motor rotation is reversed each time the switch is actuated. This feature is desirable to prevent twisting of the leads connecting the thermocouple andheater on specimen holder assembly 48 to the respective current sources and control means therefor.

lower portion of the housing 65.

ably supported upon a cap 95 by detents 96, the 1 cap 95 being force fitted upon the housing 95 and, together with the closure member 94, preventing moisture from entering at the top of the I housing 65. Closure member 94 is provided with openings 91 through which cooling fluid may be introduced into the upper part of the chamber defined by the housing 65. A Dewar type vac uum flask 98 is mounted within the housing 65 and has a downwardly protruding part 99 extending into the interspace between the metal tube 9| and the tube 49. A lead seal I99. may be provided between the part 99 andthe tube 9| to prevent coolant fluid from leaking into the As those skilled in the art will understand, the flask 98 is evacuated and provides heat insulation between the tube 49 and the housing 65. In this connection, it may also be noted that the double walled metal tube 9| provides additional heat insulation between the tube 49 and the sleeve II. It will be apparent that cooling fluid introduced through the openings 91 will flow downwardly through the interspace between the flask portion 99 and the tube 49 thereby cooling the lower portion of said tube adjacent the specimen holder. the parts in the position shown, a seal is effected at 52 between the specimen holder assembly 48 and the frustro-conical portion 99 so that no fluid flows into the subchamber 88.

The lower portion of the subchamber 88 is defined by a generally cup shaped member |9| having a threaded shank I92 which is engageable with corresponding threads provided upon a bearing block I93. This block is rotatably mounted by roller bearings I94in an insert I95 which fits into a complementary recess formed In accordance with the invention, we provide means for introducing coolingfluid into a localized area adjacent the specimen holder thereby to rapidly cool and freeze the specimen without the necessity for reducing the temperature of the entire X-ray chamber. This means preferably and advantageously comprises a subchamber 88 surrounding the specimen holder into which a cooling fluid, such as liquid nitrogen, may be introduced to quickly freeze the specimen. In the example shown, the upper part of subchamber 88 is defined by a cylindrical or sleeve member 89, preferably formed from brass, and having a frustro-conical upper end portion 99. This sleeve is supported by a double walled metal tube 9| which is carried by the member II and has its inner surface spaced from the tube 49. The upper end 99 of sleeve 89 engages the lower part of the .tube 9| and is positively retained in positionrby a set screw 92 mounted at the lower extremity of themember I I. hereinafter explained, the portion 52 of the specimen holder assembly 48 is adapted to seat against the frustro-conical portion 99 and form a vacuum tight seal therewith when the tube 49' is moved to its lowermost position by adjustment of the knob 86.

In order to rapidly and quickly freeze a specimen contained in the holder I9, a cooling fluid, such as liquid nitrogen, is introduced into the assembly 62 and, thence, into the subchamber V 88, To this end,a.closure member 94 is detach-" For a purpose to be r at the bottom of base II, an air tight seal be tween the base and insert I being provided by a grease seal I96. The bearing block I93 has a gear I98 secured thereto which may be rotated by any suitable apparatus, not shown, or by hand. ,Such rotation of the gear I98 causes a corresponding rotation of bearing block I93 which results in axial movement of the cup shaped member I9I.

Mounted at the top of the cup shaped member I9I is a brass ring I 99 which is engageable with the lower end of sleeve 89 to form a sealed joint therewith. When the parts are in the position shown, that is, when sealing ring I99 is engaged with the sleeve 89, it will be apparent that the cup shaped member I9I, sleeve 89 and the lower portion of specimen holder assembly 49 define th sealed subchamber 88 which is of smaller-dimensions than the main X-ray chamber I9, this subchamber completely surrounding the specimen contained in the holder I9. Also mounted at the top of the cup shaped member [M is a. cap H9 to which is secured one end of a bellows III, the other end of the bellows being secured, in any suitable manner, to the insert I95. This bellows effectively seals the lower portion of subchamber 88 and prevents the admission of air into the main chamber I9 through the gearing at I93 or through the bearing structure at I94, while still allowing axial movement of the cup shaped member I 9|. A circumferentialslit 2 may be provided in the cap I I9 and cup I9I to provide heat insulation between the subchamber 88 and main chamber I9.

With A may be aptuated'amanually to. permit exces'szcooliihg fluid; to drain-fromlthe subchamber 88 or: it;-may. be. actuated. automatically. to; permit the; escape of. cooling; fluid from. the. subchamber:

should the pressure thereinaraiseto an excessive. value. Assuming. that. a supply of. cooling: fluid.

issinsertedintothe assembly 62. andfills the;in:-- terspace between. the flaskportion 9'9 'and tube. 49, itwill'be apparent this .fiuid may beadmittedz into subchamber 88xby raisingthe tube 49 there: byto. disengage the portion; 52 of theaspecimen holderiassemblyv from. the frustro-conical portion. 90; Further, the cupshaped" member l'0.l together: with: the; attached sealing. member I09 is; movable: downwardly by gear I (38' to: move these parts out of the. path of the Xeray beam-.pro-

jected fromthe: slit: assembly t8;

Itwill be apparent that themain. chamber I0. is, effectively hermetically sealed. when thethreads. 44- of nut. member 4.! are engaged; to. seal the exhaustpassage to the chamber. Thus, the bellows I H seals the area between cap member H0. and insert I05, the grease seal [86. provides a vacuum tight juncture between. insert IOB-and the base ll, gasket It: provides a seal. between. the housingv l2 and base H, and grease seal 80 provides; a. vacuum tight joint between the annulargmember l9'and housing [2. In ad' dition, the gaskets 8.3.; 84. and shim: 8|. seal the area between the-sleeve 'll andannular member 79.:while the: gasket 35 andlberyllium disc 32 seal the opening through. which the X-ray beam is projected into the chamber. Finally, the engagement of. the. specimenholder assembly and annular portion. 90, at152f seals the interior of. sleeve 89, while asealing member H1. and the. tube: 9| seal the interspace between: the inner sleeve 89. andouter: sleeve H.

It. is a further feature of the invention thatv light is completely excluded from the chamber I; after the; diffraction image has. been impressed upon the; film; Thus, when the suction line is;releasedgfrom.port l5, the cap 63 prevents light from. entering from tube 40, the beryllium window 32. prevents light from entering the chamber through the slit assembly. l8 and the plugs provided. for windows 46' prevent light fromentering therethrough. Accordingly, there. is no danger of fogging of, the film after the exposure has been made due to theentrance of light into the-chamber.

The described apparatus also provides effec: tive heat insulation between the, cooled parts thereof and the exterior portions of the assembly. Thus, the area surrounding tube 491s effectively heat insulated by the Dewar; type flask;

98 and the double walledsteel tube Ill while. the lower portions of the chamber are eifective- 1y heat insulated by the slits I I2 provided in, the cup shaped member ilH. This leadsgto a very. efficient utilization of cooling; fiuid. andsa rapid. freezing of the specimen with resultant advantages in that the, crystal size is extremely small:

and the specimen is in an ideal condition. for:

a. source of X-rays isplaced.

i connectionsaremadeto the. plug-.61;

upon,. the cupmember it ismoved upwardlyuntil the; member I09. engages. and seals the lower. part of: thesleeve 89:: thereby defining the subchamber atl surrounding the specimen holder.

The tube is is removed from the frustroconicaliportion Qilandcooling. fluid is introduced through the openings 91, said fluid flowing downwardlycinto the-subchamber 38; The, specimen holder 49;is inserted whenboilingin the-Dewartype flask. has stopped. In: this manner, the specimen. is; very. rapidly cooled. and. frozen into a. suitablestate for. X-ray examination. Thereupon,.the tube 49. isloweredso that the portion 510i assembly 48.is. movedinto sealing. engagement'withthe frustro-conical portionv 90 thereby; completely'closing and sealing the subchamber; 88; At this time, a, portion of the cooling fluidis disposed. in. the subchamber 88 and an additional, portionis disposed: in the interspace betweenthe flask. portion 99 and tube 49 which maintains, the portion. of the tube adjacent the specimen; holder. at.v an extremely low. temperature. When the specimen has been cooled to the desired extent, excess liquidmaybe drained ofi; through needle valve H4 or, if the cooling fiuid; utilized is. liquid nitrogen, the. pressure within the subchamber 88; may rise to such an extent, that the needle valve is automatically actuated. During this; period, the; temperature of; thespecimen may be observed. bymeans of the thermocouple 55,. Figure3, in the specimen holder. assembly and temperature adjustments may-be made by actuating; the heater coil 5-7. It will be apparent that, during this period, the member I09 and cup shaped member I!!! obstruct the path of the X-ray beam between the slit assembly, the specimen, the beam stop, and the film.

When the specimen reaches the desired temperature, the cup member It'll is lowered and the parts IEH, I99 arethereby moved out of the path of the. X-ray beam allowing thesample to be irradiatedwith X-rays and a diffraction pattern tube impressed upon the photographic film 20. During this period, the motor 18 is actuated, causing the; specimen holder l9 to rotate while the filmisbeing exposed. Any cooling fluid remaining in the subchamber. 8.8;. of course, has diiiused. into the. mainchamber Ill and. is removed; through; the. suction line while a. vacuum is; being produced in the camera body.

After. the film has, been exposed, the valve mechanism. at 4! is actuated to admit air into the chamber and. to force. cap. 53i into engagement with the end of tube 40. Thereupon, the suctionline may be removed without the danger of, light. entering. the chamber. The apparatus may then. be .takeninto. a darkroom for removal of. the film..

It: will. be apparent; that the described app atus; offers a number of important advantages. Thus,.the. cooling fluid is utilized only in a limited. area surrounding the specimen, this area being: defined. by thev subchamber 88, and it is not necessary to cool the whole interior-of the mainXi-ray chamber [1].. Further, the apparatus of. our invention provides a clear unobstructed path for the X-raybeam afterthe specimen has been cooled to the. desired. temperature and the apparatusnfor accomplishing this result iscom- A'. small? amount of. liquidv material". to.

temperatures.

pletelysealed so that there is no interference with the X-ray diffraction pattern. The use of the subchamber 88 enables specimens to be very quickly frozen so that crystals may be obtained of such small size as to be very desirable for X-ray examination. The provision of the heater and thermocouple adjacent the specimen holder provides a very accurate and close control of specimen temperature over a range of temperatures which is desirable in order to study phase transitions, or the coeflicient of expansion of various materials. Finally, the construction is such that the desirable rotary movement of ly employed for obtaining diffraction patterns of frozen hydrocarbons and hydrocarbon mixtures. The apparatus is also applicable to many polymers and organic materials, particularly rubber, which give poor diffraction patterns at ordinary The diflraction patterns obtained with our present apparatus with such materials are very clear and more sharply defined than has heretofore been possible.

While the inventionhas been described in connection with a present, preferred embodiment thereof, it is to beunderstood that this description is illustrative only and is not intended to limit the invention, the scope of which is defined by the appended claims. 7

What is claimed as new and desired to be securedby Letters Patent is:

1. In X-ray diffraction apparatus, an X-ray chamber, means for evacuating and hermetically sealing said chamber, a support for a film and a specimen holder in said chamber, a guide for directing a beam of X-rays against said specimen holder for diffraction against said film support, means defining a subchamber surrounding and completely enclosing said specimen holder, and means for introducing cooling fluid into said subchamber.

2. In X-ray diffraction apparatus, an X-ray chamber including a specimen holder, a support for a film, and means for directing a beam of X-rays against a specimen in said holder thereby to produce a diffraction pattern upon a film in said support, means for evacuating and hermetically sealing said chamber, a pair of relatively movable members which are engageable to define a sealed coolant chamber within said X-ray chamber and surrounding said specimen holder, and means for introducing coolin fluid into said coolant chamber.

3. In X-ray difiraction apparatus, an X-ray chamber including a specimen holder, a support for a film, a slit assembly for directing a beam of X-rays against a specimen in said holder thereby to produce a diffraction pattern upon a film in said support, means for evacuating and hermetically sealing said chamber, a pair of relatively movable members which are engageable to define a sealed coolantchamber Within said X-ray chamber and surrounding said specimen holder, said members, in their engaged position, obstructing the path of the X-ray beam between said slit assembly and said specimen, means for introducin'g cooling fluid into said coolant chamber, and means for moving said members to a spaced position to provide an unobstructed path between said slit assembly and said specimen holder.

4. In X-ray diffraction apparatus, an K-ray chamber includingea specimen holder comprising a beryllium'tube of capillary dimensions having a quantity of liquid test material therein, a support for a film, and means for directing a beam of X-rays against said tube thereby to produce a,

diffraction pattern upona film in said support, means for evacuating and hermetically sealing said chamber, a pair of relatively movable sealing members which are engageable to define a coolant chamber within said X-ray chamber surrounding said tube, said sealing members, in their engaged position, obstructing the path of the X-ray beam between said slit assembly and said tube, means for moving said members to a spaced position to provide an unobstructed path between said slit assembly and said tube, and means for intro ducing cooling fluid into said coolant chamber thereby to freeze the liquid in said tube. 5. In X-ray diffraction apparatus, an X-ray chamber including a rotatablespecimen holder, a support for a film, and guide means for directing a beam of X-rays against a specimen in said holder thereby to produce a diffraction pattern upon a film in said support, means for evacuating andhermetically sealing said chamber, a pair of relatively movable sealing members whichare engageable to define a coolant chamber within said X-ray chamber surrounding said specimen holder, one of said members including a needle valve communicating with the coolant chamber torelieve excessive fluid pressures therein, said members, in their engaged position, obstructing the path of the X-ray beam between said guide means and said specimen, means for introducing cooling fluid into said coolant chamber when said members are in their engaged position, and means for moving said members to a spaced positionto provide an unobstructed path between said guide means and said specimen holder.

6. In X-ray diffraction apparatus, a chamber having an arcuate, interior portion which is adapted to receive a film, means for evacuating and hermetically sealin said chamber, a beam stop in said chamber, a slit assembly for directing a beam of X-raysagainst said stop, a specimen holder assembly mounted for rotary movement relative to saidchamber and having a sleeve portion protruding into. said chamber, a carrier in cluded in said assembly which is movable axially of said sleeve portion into and out of sealing engagement therewith, a specimen holder supported by said carrier and movable therewith to a position between said slit assembly and said stop thereby to deflect a part of the X-ray beam onto the arcuate portion of said chamber, a cup shaped member in said chamber which is movable axially into sealing engagement with said sleeve portion thereby'defining a subchamber surrounding said specimen holder, means for moving said carrier out of engagement with said sleeve portion to permit introduction of cooling fluid into said subchamber thereby to freeze a specimen in said n recting a beam of X-rays against saidstop, a specimen holder assembly mounted for rotary movement relative to saidchamber, said assembly including asleeve protruding into saidchamberhaving a frustro-conicali-nner portion, acara rich .forming a part of said assembly which. is movable axially of said sleeve portion into and .out of sealing engagement withsaid frustro-conical portion, a specimen holder supported by said carrier and movable therewith to aposition between said slit. assembly and .said sto thereby to .diifract a part :of the X-ray beam onto a film .heldby. the arcuate portion of said: chamber, a member. in=said chamber which is movable axially I into. sealing engagement with said sleeve thereby defining a subchamber surroundingsaidspecimen ..liolder,,. said. member obstructing the-path of the X-ray beam when. it is insuch engaged position, means for moving. said carrier out of engagement withsaid frustro-conicalportion to permit introduction of. cooling fluid into. said subchamber thereby to. freeze a specimen in said holder .andfbr moving. said carrier into sealing engagement with saidsleeve portionlafter sufiicient cooli'ngifluid has entered the subchamber, and. means for moving .said cup shaped member to a position spaced from said sleeve to provide an unobstructed path for the X-ray beam between said slit assembly andsaid specimenlholder.

8. A cooling chamber assembly iorquickvfreezing. of a specimen to be subjected tocrystallographic X-ray. analysis which comprises a rotatable specimen holder assembly including a sleeve, a tubular member axially movable .relative to said sleeve,-a specimen holder assembly 7 secured to said tubular member and adapted for sealing engagement with said sleeve, .a second assembly including a support, a member axially movable on said support and adapted for sealing engagement with said sleeve toldefi'ne a cooling chamber surrounding said specimen holder assembly, whereby cooling fluid may be supplied to said chamber through th interspace between said tubular member and said sleeve to quickly freeze a specimeniin said holder assembly.

9; A cooling chamber assembly for quick freezing of a specimen to be subjectedto crystallographic X-ray analysis which comprises a rotatable specimen holder assembly including a sleeve having a frustro-conical portion, atubular member axially movable relative to said sleeve, aspecimen holder-assembly secured to said tubular member and adapted for sealing engagement with said frustro-conical portion, and heat insulating means closely spaced with respect to the outer surface of said tubular member, a second assembly including a support, a generally cup shaped member threaded to said support and axially movable thereon, said cup shaped member being adapted for sealing engagement with said sleeve to define a cooling chamber surrounding said specimen holder, whereby coolin fluid may be supplied to said chamber and to the interspace between saidtubular member and said heat insulating means thereby to uickly freeze .a-specimen in said-holder assembly, and a bellows secured to said support and said cup shaped member to seal the threaded joint therebetween.

KARL E. BEU. HOWARD H. CLAASSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,904,392 Stintzinget-al. Apr. 18, 1933 2,341,108

OTHER REFERENCES McLachlan, Jr Feb. 8, 1944 

